Frogs are ectothermic, which means that they rely on their environment to regulate their body temperature. The bodies of ectotherms reflect the air, ground, and water temperatures around them. One advantage that ectotherms have over mammals is that they can survive for long periods without eating. Common Frogs can survive temperatures as low as six degrees Celsius. They can do this by producing a natural anti-freeze that stops them from freezing. Frogs can control their temperature with their bodies, for example by changing their color to affect how much solar radiation (heat from the sun) they receive, or absorbing or evaporating water through their skin. Temperature affects rate of growth, digestion and most bodily processes, heat increasing the rate of growth and cold slowing it. Tadpoles and developing frogs are more susceptible to temperature than adults.
In the fall, frogs first need to find a place to make their winter home, a living space called a hibernaculum that will protect them from weather extremes and from predators. The frog then “sleeps” away the winter by slowing down its metabolism. When spring arrives, it wakes up and leaves the hibernaculum, immediately ready for mating and eating. They emerge from hibernation around February and March.
American bullfrog, an aquatic frog, usually hibernate underwater in streambeds or on pond bottoms. Because aquatic frogs need oxygen, they lie just above the mud, or only partially buried in the mud, so they are near the oxygen-rich water. They may even occasionally slowly swim around.